With the development of science and technology and the improvement of people's living quality requirements, requirement on the variety of lighting products becomes higher and higher. How to manufacture a lighting device meeting the requirements of people is the greatest concern of each enterprise related to lighting industry.
In secondary optical design, collimation design has been most studied by those skilled in the art, that is, divergent ray of light emitted from a point light source is converted into a parallel light beam or an approximately parallel light beam by a light guide which is designed correspondingly, so as to improve directivity and uniformity of the ray of light emitted from the light source.
However, only a parallel light source is arranged in a lighting device with parallel light source in the prior art, thus the shape of the light-emitting surface of the lighting device with parallel light source is simple and user's requirement on the variety of the lighting effect of the lighting device with parallel light source cannot be satisfied.